Chronic Thromboembolism Phenotypes after Acute Pulmonary Embolism: Identification with the SEARCH Algorithm

RATIONALE: Chronic dyspnea and exercise impairment are common after acute pulmonary embolism but poorly characterised. OBJECTIVES: We performed a prospective observational study to validate an algorithm to diagnose discrete post-pulmonary embolism outcomes, including chronic thromboembolism phenotypes. METHODS: emodynamic measurements by rest and exercise right heart catheterisation. Clinical data were reviewed after the first post-pulmonary embolism evaluation and then six months later. MEASUREMENTS AND MAIN RESULTS: Symptomatic recovery was most common and occurred in 66.2% of patients during the final evaluation. Dyspnea without discernable physiological defects occurred in 2.1% and dyspnea from alternative diagnoses in 19.7%. Chronic thromboembolism phenotypes were diagnosed in 12.0% of patients. Chronic thromboembolism with ventilatory inefficiency and/or small stroke volume augmentation during exercise was seen in 6.3%: 2.1% without pulmonary hypertension on right heart catheterisation and 4.2% in whom right heart catheterisation was not performed. Chronic thromboembolic pulmonary hypertension and chronic thromboembolism with exercise-induced pulmonary hypertension occurred in 2.1% and 3.5%, respectively. Krippendorff's alpha among the readers was 0.984 (95% CI: 0.9663, 0.9960), signifying very high diagnostic reliability. No patient developed chronic thromboembolism between the first and final evaluations. CONCLUSIONS: Dyspnea from chronic thromboembolism is common after acute PE, most of which is not associated with pulmonary hypertension. The SEARCH protocol reliably identifies chronic thromboembolism phenotypes after acute embolism.